Structure, mechanical properties and thermal stability of Ti1-xSixN coatings

Ti1-xSixN coating is a promising candidate for wear resistant applications due to their super-hardness and high thermal stability. Here, we explored the structure, mechanical properties and thermal stability of Ti1-xSixN (x = 0, 0.13, 0.17 and 0.22) coatings deposited by cathodic arc evaporation. Monolithically grown Si-containing Ti1-xSixN coatings, which are Si-solution in TiN for x = 0.13 and 0.17, reveal a high hardness of 39.4 ± 0.67 and 40.6 ± 0.72 GPa, respectively. Then Ti1-xSixN transforms into a nanocomposite structure consisting of cubic Ti(Si)N nanocrystallite enveloped by the amorphous SiNx tissue phase for x = 0.22, which exhibits a high hardness of 40.0 ± 0.6 GPa. However, increasing of Si content leads to a significant increase in compressive stress from −0.63 GPa for x = 0 to −3.78 GPa for x = 0.13 to −4.54 GPa for x = 0.17 to −5.51 GPa for x = 0.22. The hardness of Ti1-xSixN coatings can be maintained up to ~ 1000 °C due to the suppressed grain growth, and then decreases for further elevated annealing temperature, whereas the TiN coating exhibits a continuous drop in hardness towards its intrinsic value of ~ 21.3 GPa.